Protective device for fuel lines or the like



1950 L. A. WILLIAMS, JR., ETAL 2,531,958

PROTECTIVE DEVICE FOR FUEL LINES OR THE LIKE Filed Dec. 18, 1942 Patented Nov. 28, 1950 PROTECTIVE DEVICE FOR FUEL LINES OR THE LIKE Lynn A. Williams, Jr., and Arthur C. Allen, chicago, Ill., assignors to Stewart-Warner Corporation, Chicago, 111., a corporation of Virginia Application December 18, 1942, Serial No. 469,420

3 Claims. (Cl. 137139) The present invention relates to protective devices for fuel lines and the like, and is more particularly concerned with preventing the excessive loss of gasoline or other fluids from the fluid conduits when these conduits become perforated.

Recently the use of self-sealing fuel tanks in airplanes, particularly military airplanes, has received considerable attention, inasmuch as the leakage of fuel from a perforated fuel tank Will result in the airplane having to discontinue flight the tape shown in Figure 2 or 3 around a pipe sooner than was anticipated at the time of the fitting; and take-off. Another danger is that the gasoline Figure 6 is a side elevation of a portion of the thus released may catch fire and destroy the mechanism shown diagrammatically in Figure 1. aircraft. Similarly, the perforation of a fuel line 'In Figure l, we have shown a Wheatstone will lead to the same result. However, the probbridge formed of the branches I0, l2, l4 and I6 lem of preventing the escape of gasoline or other connected to a relay coil it in a well knownmanfuel from a fuel line cannot be solved by providner. Three of the branches, H3, l2 and M, of ing self-sealing fuel lines, since these lines are the bridge are adjustable so that the bridge can comparatively small and sections thereof may be be balanced with respect to the fourth branch completely shot away. Also it would add con- It, so that when the bridge is properly balanced siderable weight to the structure to provide fuel no current will flow in the coil I8. The coil l8 lines of the required size if these lines were to be therefore remains unenergized, thereby permitof aself-sealing type. tin current to flow through the contacts of The present invention is concerned with prothe relay, and a solenoid valve 22. The valve is viding an arrangement for automatically pretherefore energized and is of the type which reventing the flow of fuel or other fluid through mains open so long as energized. a perforated conduit, thus preventing the escape Whenever the relay coil I8 is energized through of the fluid. As an example, an airplane can be unbalancing of the bridge, the contacts 20 will equipped with duplicate fuel lines as taught by be separated, thereby deenergizing the solenoid the present invention so that if one of these fuel valve 22. The solenoid valve under these condilines becomes perforated it will be automatically tions closes off communication between the two closed, fuel then flowing to the aircraft engine portions 24 and 26 of the conduit connected through the second parallel conduit. thereto. One of these portions, for instance the It is therefore the principal object of the presbranch 24, leads to the fuel tank while the other ent invention to provide a novel arrangement for branch leads to the airplane engine. When the preventing the escape of fluid from a fluid line solenoid valve 22 closes, therefore, fuel cannotwhen the line becomes perforated. flow beyond the valve 22. It therefore cannot :An additional object of the present invention escape through any perforations in the branchis to provide novel mechanism for closing valves 26. Ordinarily valve 22 will be connected directly when afuel or other fluid line becomes perforated. to the fuel tank or at least to a short branch Yet another object of the present invention is which in turn is connected to the tank. The to provide novel mechanism for indicating at a branch 24 therefore may be considered as comremote point that a conduit has become perfoparatively short, while the main portion of the, rated. fuel line to the engine is comprised of the branch Other objects and advantages will appear from 26. the following description of a preferred embodi- The branch it of the Wheatstone bridge may. ment of my invention illustrated in the accombe formed as shown in Figure 2. It is comprised pa y drawings, in which similar characters of a wire 28 which is shaped to a sinuous conof reference refer to similar parts throughout the figuration and is disposed between two layers of several v1eWs. 5 insulating tape 39 which are secured together the after the Wire is in place. This tape is wrapped F' 1 1s a d a am atic representation of aparound the conduit 26 as shown in Figure 4 so pa atus emb dy ng the present invention appl d that it covers the same and is secured thereto. to an airplane l line; Thus. the pipe 26 is closely covered by a network Figure 2 is a perspective view of a pipe-covercomprised of the wire 28 insulated between the tion;

form of tape which may be used in carrying out the present invention;

Figure 4 is a side elevation of an airplane fuel line conduit being covered with the tape shown in Figure 2 or 3;

Figure 5 shows one arrangement for carrying Figure 3 is a perspective view of an alternative rupt the flow of fuel or other fluid through the" pipe 26.

In Figure 3 is shown an alternative type of tape which may be used for the same purpose as that shown in Figure 2. -In this tape the warp 32 is made up of metal strands, while'thewoof 34 is formed of fabric or some otherin' sulating material. The warp'strands'3'2' are'con-- nected alternately at their ends so that the current flows back and forth the length of the tape in a zig-zag manner; thus breaking of any of the wairp strands 32 will ihte'rlupt'the current flow. For instance, considering the outside warp strand at one edge of the tape as being iridic'atediby the letter A while" the next is indicat ed by the letter B and so on, these strands are connected so that at one end ofthe tape A is connected to B, at the opposite end of the tape B is connected to C, at the first end of" the tape disconnected'top, so

its-shown iii-Figure 5-, when afitting 34-i-sen-' countered, the tape may merely be spread at this point to pass to one sideoi the fitting; prerit slibllld 'pa's S0 21S t0 COVGl" as Iilllfi Of the Ti ng as possible so that a bullet hitting the fitting will inall probability also hit the tape. In Figure e we have snowna box or containing the relay and bridge shown in Figure '1 though these elel'nents'rnay' be of any suitable form, in the device illustrated, the relay is ino'unt' in one end" of the boxw-hi lethe three ele merits lii; l2 and [4 of the bridge are located adjacent thereto. These resistance elements have slotted'stems'so that they can be adjusted by means of a screwdrive'r from the frontof the case. At each end tne box is equipped with standard A. N. type 'fittin'gs'iib to which the electrical' connections are made.

it will be appreciated that although we have shown a solenoid Valve of the type which remain open when energized and closes when de energized; adifferent ty e of valve may b used if desired; If the valve is of the type which nor-' mally remains open and closes when energized, then the contacts 28 would be placed upon the opposite ide of the relay armatureand would F be normally open excepting when the coil (8 is energized. It will be ap reciated also that an indicating instrument can be substituted for the coil 18. In this event the relay contacts 'z 'c-anri;

solenoid valve 52 could be replaced by a hand operated valve which would be closedbythe pilot whenever the indicating instrument indicated the new ofan electrical current t'neretnrougli,

Having thus described our invention, What claim as new and desire to secure by Letters Pat eat or the United States is:

in protective system for a fuel c-onduitim eluding a valve biased to closed position, elec tromagnetic means for opening said valve, a-ncl reallyclosed. electric circuit for energizing electromagnetic means, a relay circuit iii-ran d' and associated with said normally closed so uiotwhen energized the normally closed circ'uit isdeeliergized, a balanceable bridge circuit so associated with the relay circuit as to e fiergize the relay circuit when unbalanced and effect deenergization of the relay circuit when balanced, one of the legs of the bridge including a strip of tape of insulating material, a wire network in face to face relationship with the tape, a second strip of insulating tape secured in face to' face relationshi to the first strip and acting with said first-strip to enclose said network, said network having a width at least substantially equal to the circumference of the conduit so that-when the composite tape is wrapped around saiclconduit the networkwill substantially completely enclose said conduit while being insulated therefrom and from adjacent objects by said tapes:

'2. A protected conduit including a valve biased to closed positioni electromagnetic means arranged to open said valve when energized, a normally closed electrical circuit for energizing said electromagnetic means, a relay circuit associated'withsaid normally closedcircui t and arran'ged when energized to eifect deenergization of said normally closed circuit, abridge circuit associated with said relay circuit so as to deenergiz'e a; valve biased toclosed position for controlling flow through said fuel line, electromagnetic" means for opening when energized said valve,

a normally closed electric circuit for energizing said electromagnetic means, a rela circuit as sociated with said normally closed circuit and arranged when energized to effect deenergiza tion of" said normally closed circuit, a balanceable bridge circuit so associated with said relay circuit that when balanced the relay circuit is deenergized and when unbalancedthe relay circult becomes energized, said bridge circuit including a wire network surrounding the fuel line arranged to effect unbalance of the bridge cir= edit on forceful rupture of the fuel line;

LYNN A. WILLIAMS, JR. ARTHUR C. ALIEN;

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FGREIGN PA-"IEl-WIRS- Number Country Date 433,364 Great: Britain-acfi-asscswaoi 1935 

